明矾石综合利用技术研究进展

明矾石是未大规模开发利用的富含K、Al、S的矿物。为了推动明矾石综合利用技术的进步,促进明矾石的大规模开发,在概述了明矾石的基本性质,国内分布情况及资源化综合利用研究现状的基础上,分析了各技术路线中影响明矾石大规模产业化开发利用所存在的问题,对比了高温焙烧工艺和热压浸出工艺的技术特点和工业化难度,指出明矾石的高温焙烧工艺虽都能实现钾、铝元素的提取,但是工序复杂,成本高,焙烧能耗大,该技术方向降本潜力小,因而工业化难度大;而直接热压浸出明矾石工艺没有明矾石的焙烧工序,且浸出过程中的热量易于回收利用,因而该工艺具有能耗和成本低,投资小,工艺简单,流程短等优势。其中的碱法工艺与高温焙烧工艺相比,省去了球磨磨矿、高温焙烧脱水、还原和硫酸制取等工序,流程大为缩短,能耗明显降低,且无废气、废灰,减少了环境污染,但该法存在浸出过程中烧碱消耗量过大,碱原料成本高,对含硅高的明矾石还存在氢氧化铝提取成本太高的问题。而直接加压酸浸工艺对明矾石的品位要求不高,产品硫酸钾、氢氧化铝、石膏等具有极大的市场容量,因而适合大规模产业化开发。

Research Progress on the Comprehensive Utilization of Alunite

Alunite,as a kind of K-,Al-and S-rich mineral,has not been effectively utilized. Aiming to promote the devel-opment of large-scale and improve comprehensive utilization of alunite,Based on an overview of the basic properties,domestic distribution and the current research status of alunite concerning comprehensiveutilization of resources,the issues with the tech-nical routes that limit the industrial-scale utilization of alunite are analyzed,and the comparison of high-temperature roasting and hot-pressing leaching regarding their technical characteristics and industrializing barriers are also reported. It is shown that the high-temperature roasting method can reach the goal of extracting potassium and aluminum,but it has the defects of too complicated process,high costs,high energy consumption,little potential to cut the costs,resulting in major difficulties in its in-dustrial development. While,the direct hot-pressing leaching method,has no calcination process and the heating energy is recy-cled easily in the leaching process. It,therefore,has the advantages of low energy consumption,small investment and simple process. Compared with high-temperature roasting process,the alkaline process does not contain the steps of ore grinding,roast-ing at high temperature,reduction and sulfuric acid making,which makes its process largely simplified and energy consumption reduced. Moreover,the environmental pollution in this process is also reduced since it does not have waste gas and dust. How-ever,this process consumes significant amount of NaOH,resulting in high costs for the alkali usage and the extraction of Al (OH)3 from Si-rich alunite. While,the direct acid leaching process does not have high requirement for alunite′s grade and its products of potassium sulfate,aluminum hydroxide,gypsum have huge market capacity,which is suitable for a large-scale in-dustrial development.